The antecedents of a naturalistic ethics, however, are not all located in one man. With varying emphases, we find similar tendencies appearing in Aristotle, in Leonardo da Vinci, in Hobbes, in Spinoza, in John Stuart Mill, in Herbert Spencer, and in many other wise and kind men. Today this same influence is more aggressive and expanding than ever before. Lucien Levy Brühl, Edwin Holt, John Dewey, William Morris Davis, George Clarke Cox, and Roy Wood Sellars are typical representatives of the movement devoted to making ethics as objective as the science of mechanics. Consequently it would seem that the attempt we shall make here to define ethical values in terms of man’s biological functions is not a forlorn hope, either historically unforeseen, or lacking contemporary sympathizers. What, then, is implied by the statement that ethical values are to be defined in terms of man’s biological functions? In the first place, we imply that just as man’s body, by means of brain, sense organ, muscle and gland, makes, upon stimulation, all the mind it ever manifests, so likewise that same body of man, through the mechanisms just enumerated, creates ethical notions. That is to say, the realm of ethics is coincident with the realm of human behavior in so far as that behavior is judged to be good or bad, right or wrong, virtuous or vicious. Now the body of man performs many and various functions, some of which are called physical, some chemical, some mental, and some ethical; and any structure of man’s body, such as an arm or a leg, can be shown to perform all these four types of function at the same time. Such a statement will cause no surprise to those who have followed the trend of psychological and ethical theory in the last decade. And while it is obviously impossible to prove any theory to the negatively suggestible obstructionist, it is a very hopeful sign that today great numbers of even untutored men are disbelieving in the transcendence of mental and ethical qualities, and are relocating them among the natural phenomena of the world. Hereafter, then, we shall also understand ethical values to be achievements of man’s mind, which is a function of his protoplasm, which is a function of the sun.